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If you have gasoline that’s a year old in a car, can you use it? Some people say yes, others say no. We’ll get the advice from some experts in the field and look at some of the things you can do to make sure that older gas doesn’t damage anything to your car.

Old gasoline has degraded

Gasoline is a highly refined product with very specific characteristics. One important characteristic of gas is its volatility, or how easily it vaporizes. The most volatile components in gasoline evaporate first because they are the lighter components of the mixture. Unfortunately, these volatile components are important for the gasoline to burn properly. If they have vaporized away, the result is diminished engine performance and hard starting.


Above, we saw the “aging” of gasoline in terms of losing volatile components. The other degradation that can happen is oxidation. Oxidation occurs when the oxygen molecules in atmospheric air react with the hydrocarbons in gasoline. The result of this reaction is the formation of gum and varnish compounds. The service department at Trinity Chrysler, a local Chrysler, Dodge, Jeep, Ram dealer in Taylorsville, IL, warns that these compounds can clog up gas lines and filters as well the small orifices in carburetors and in fuel injectors. Unfortunately, removing this gunk can be expensive and your vehicle may not run very well until everything is cleaned out.


When outside temperatures cycle up and down a lot, water can condense on the walls of gas tanks or storage containers. Accord to our technical sources, fuels such as E85, which have a high concentration of ethanol alcohol may be even more susceptible to water contamination because ethanol absorbs water. You can reduce the chances of water contamination by keeping your car’s gas tank as close to full as possible.

How do you identify bad gas?

Bad gas isn’t hard to identify. First concept: if it’s been sitting for 6 months or more, it’s probably turning bad. A common way to verify this is to simply smell the gas. Old gas has a distinct odor to it. Some say it has a pungent smell like old paint thinner. Another thing old gas does is turn a dark color.  You can check stored gasoline by pouring some into a clear glass container and comparing it side-by-side with known fresh gasoline.

Can you storage gasoline for a long time?

If you know gas will sit in your tank or a storage container for a while, then it’s a wise move to buy some fuel system stabilizer and mix it in with the gasoline. The stabilizer helps prevent oxidation, the nasty process that turns gasoline into garbage that gunks up your system and leads to expensive repair work.

Why not just drain the tank?

Using fuel system stabilizer for extended storage is preferable to draining the tank and leaving the system dry. Dry fuel systems allow rubber hoses, gaskets and seals to dry-rot and crack, possibly leading to leaks. In addition, a dry system can expose the insides of metal fuel lines and your gas tank to air and moisture, which can lead to the formation of rust.


If you have to store something gasoline-powered for a long time, consider putting fresh gas in it and a good stabilizer. If you have a piece of equipment that has old gas in it, try to drain out as much as you can and then add fresh gas. With a little luck, it will startup and run.


Earthgarage – Greener Car. Fatter Wallet.